The present invention relates to a plated resin product in which a metal film is formed on a resin base including an edge and to a method for manufacturing the plated resin product.
When a plated resin product in which a metal film is formed on a resin base is manufactured through electroplating, the metal film is formed on a plated portion of the base by forming an electroless plated thin film on the surface of the base and then performing a number of processes. The plated resin product, which has undergone plating in such a manner, has a metallic luster that is in accordance with the types of plating components.
When electroplating is performed, the base is held by a jig and immersed in an electroplating tank including an anode electrode. An anode voltage is applied to the anode electrode, and a cathode voltage is applied to the base through the jig.
The plated portion may include an acute edge. When a plated portion having such an edge is electroplated, electric charges in the electroplating solution are apt to concentrate at the edge rather than other sections of the plated portion. This increases the amount of plating metal deposited onto the edge. Thus, the metal film at the edge becomes much thicker than other sections of the plated portion. This lowers the aesthetic appeal of the product.
Japanese Laid-Open Patent Publication No. 2008-169403 discloses a plated resin product in which a base is formed integrally with an auxiliary plated portion (sacrificed portion) that extends to the vicinity of an edge and functions as an auxiliary cathode electrode. The auxiliary plated portion is spaced apart from the edge by a predetermined distance so that the auxiliary plated portion does not contact the edge. Thus, when a cathode voltage is applied to the base during electroplating, the auxiliary plated portion is negatively charged, together with other sections of the base, to function as an auxiliary cathode electrode. As a result, positive electric charges of the metal component dissolved in the electroplating solution collect near the auxiliary plated portion so that the concentration of the electric charges at the edge is limited. This limits the concentration of plating metal deposited onto the edge and forms a metal film having a relatively uniform thickness.